Matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) has traditionally used an organic matrix in the ionization process to obtain spectra of high molecular weight molecules such as synthetic polymers, carbohydrates, proteins, and nucleotides. Unfortunately, the application of MALDI to small molecules (MW<1000 Da) such as lipids has not been as successful due to interference from matrix peaks in this mass region of the spectrum. Several strategies have been explored to minimize this effect including the development of numerous matrix-free systems which generally involve interactions between the analyte and a functionalized surface, during laser irradiation. The most notable matrix free system is from Siuzdak and co-workers describing desorption/ionization on porous silicon (DIOS). The major problems with the silicon surfaces however, have been the lack of reproducibility in manufacturing and the inability to efficiently ionize non-basic compounds such as lipids.
The present disclosure addresses these and other needs.